ROCKLAND, Maine — It’s been quite a year for L. Frank Baum and his most famous creation, the land of Oz. In March, “Oz the Great and Powerful” opened. The film, which stars James Franco, Michelle Williams, and Rachel Weisz, has so far grossed just under $500 million worldwide. In September, a 3-D version of the 1939 “Wizard of Oz” played in theaters and was released on disc.

Millions clearly remain willing — nay, eager — to follow the Yellow Brick Road. Through March 30, that road leads to an unexpected destination. The Farnsworth Art Museum becomes an outpost of the Emerald City, with its exhibition “The Wonderful Wizard of Oz: Selections From the Willard Carroll/Tom Wilhite Collection.”

Why Maine? Carroll and Wilhite are Hollywood producers (and personal and professional partners) who now live in Camden. They own more than 50,000 items related to Baum’s “Oz” books and the several movies and stage plays derived from them. It’s the largest single collection of Oz memorabilia, and Carroll and Wilhite eventually hope to display it in a National Oz Museum, in Camden.

In the meantime, there’s this charming show. It consists of 105 items. Highlights include a shooting script from the movie (it belonged to Bobby Connolly, who staged the musical numbers), the large hourglass the Wicked Witch of the West has in her castle, and a costume worn by one of the Munchkins in the Lollipop Guild scene.

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A poster for the 1955 British reissue of “The Wizard of Oz.”

The movie takes pride of place, right down to a video of excerpts and another of interviews with Carroll; Munchkin Margaret Pellegrini, who died in August; and the son of Margaret Hamilton, whose Wicked Witch scared the bejesus out of any child who ever saw the movie. Speaking of bejesus-scaring capability, there’s also a miniature model of one of the Wicked Witch’s flying monkeys, which you could argue were even scarier than she was.

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The rest of the Oz universe is acknowledged too: from posters for the ’70s musical “The Wiz” (both stage and film versions) and “Wicked” to first editions of 14 of Baum’s 17 “Oz” books (the copies looking well and happily used) to one of John R. Neill’s original illustrations for “The Road to Oz.”

Some of these items, like the witch’s hourglass or an early version of Dorothy’s blue gingham jumper, are the movie equivalents of religious relics: objects that go beyond mere nostalgia to something like transcendence. The most famous item associated with the movie, a certain pair of ruby-red slippers, aren’t here. They’re at the Smithsonian National Museum of American History, in Washington, D.C. What is here are ruby-red slippers worn in the 1985 film “Return to Oz.”

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A shooting script for “The Wizard of Oz,” with a dress tested by Judy Garland for the movie and the blouse she wore during the first two weeks of filming.

The script and hourglass and dress are the stars of the show. But what may be the most illuminating items are some of the ephemera from throughout the Oz canon: soap, an Oz-themed box of Whitman’s candy (do the original contents remain inside?), playing cards, a board game, dolls, wallpaper, buttons, and so on. The shrewdest business move in Hollywood history was George Lucas’s retaining all rights to toys and other ancillary products from “Star Wars.” But entertainment tie-ins didn’t begin a long time ago, in a galaxy far, far away. They date at least to the early 20th century, in the good old US of A, as numerous examples here from “Oz” books and stage shows attest.

Not that Oz appeal is exclusively American. That’s true now: More than half of the grosses for “Oz the Great and Powerful” have come from outside the United States. It was true then. TheFarnsworth show includes posters for Italian and British releases of the film, as well as a tie-in book in Portuguese and another in Swedish, a Soviet adaptation of the story, and a Latvian translation of the novel. Oz lies over the rainbow. Everyone knows that. What they may not realize is that not just Kansas lies beneath it but pretty much everywhere else too.